A device for raising and lowering a load, such as a forklift, has a hydraulic cylinder for moving the load up and down by extension and retraction through supply and discharge of a hydraulic pressure. The hydraulic cylinder is single-acting. The hydraulic cylinder extends as a hydraulic pressure is supplied to a hydraulic chamber inside a cylinder tube, and retracts as a hydraulic pressure in the hydraulic chamber is discharged.
JP 9-317717A describes a hydraulic cylinder that has a cushioning function for alleviating impact by suppressing an ascending speed of a piston when reaching a stroke end. The cushioning function is realized by an orifice that is provided in a piston rod of the hydraulic cylinder in the vicinity of the piston, and that allows the inside and outside of the piston rod to communicate with each other. That is to say, when cushioning oil, which is working oil between a cylinder tube and the piston rod, flows into the inside of the piston rod via the orifice in the vicinity of the stroke end, flow resistance is applied to the working oil. As a result, the ascending speed of the piston is reduced.
Also, a communication passage and a check valve are built in the piston. The communication passage allows the inside of the piston rod and a hydraulic chamber to communicate with each other. The check valve is provided in the communication passage and permits only the flow from the inside of the piston rod to the hydraulic chamber. In this way, in a case where there is excess cushioning oil due to upward leakage of the working oil from the hydraulic chamber past an oil seal provided on an outer circumference of the piston, the extra working oil can be returned to the hydraulic chamber.